Enzymatic biodegradation of 2, 3-dihydroxybiphenyl and amplification of encoding enzyme gene

The crude extracts of a novel biphenyl-degrading bacterium, Dyella ginsengisoli LA-4, can transform 2, 3-dihydroxybiphenyl, catechol and 4-chlorocatechol into the corresponding ring meta-cleavage products. And it was proved that the enzyme was a constitutive 2, 3-dihydroxybiphenyl 1, 2-dioxygenase. The specific activities were 7.37, 0.2 and 0.06 U/mg, respectively. The effects on enzyme activities by metal ions and some inhibitors were observed. The results indicate that Fe²⁺ can enhance the transformation of catechol and 4-chlorocatechol, but it inhibits the transformation of 2, 3-dihydroxybiphenyl. Because the enzyme activities were completely inhibited in the presence of over 1 mmol/L H₂O₂, it is determined that the enzyme is an Fe (II)-dependent extradiol dioxygenase. A conserved region of the 2, 3-dihydroxybiphenyl 1, 2-dioxygenase gene bphC was amplified by PCR, which shows 73% similarity with that of known bphC gene.